1. Field of the Invention
This invention relates to a two-stroke cycle reciprocating internal combustion engine for spark ignition and crankcase scavenging, comprising a fuel injection nozzle and an arbitrarily operable throttle valve, which is provided in an air intake passage upstream of leaf spring dampers, which are biased in a cloging sense.
2. Description of the Prior Art
In known two-stroke cycle internal combustion engines of that kind there is a relatively large distance or read space between the throttle valve and the leaf spring dampers, which open and close in dependence on the pressure difference between the air intake passage and the crankcase, and there is also a large distance between the throttle valve and the fuel injection nozzle. Besides, the flow areas of the intake passage downstream and upstream of the throttle valve are substantially equal. For this reason the reduced velocity of flow of the fresh air during an operation of the engine under light load will result adjacent to the fuel injection nozzle in the formation of a poorer mixture, which contains relatively large droplets. A poor mixture will obviously adversely affect the composition of the exhaust gas.
If the fuel injection is electronically controlled by a sensor which detects the instantaneous position of the throttle valve a fast opening of the throttle valve will cause the quantity of injected fuel to be increased as a result of the next computing operation. But it will then be necessary to accelerate the relatively large quantity of which is contained in the entire intake system and this requirement will delay the response of the internal combustion engine and will also result in a poorer composition of the exhaust gas because the fuel-air mixture has an unfavorable composition.
In austrian Patent Specification No. 391,351 it has already been proposed to arrange the fuel injection nozzle in an oblique position i the cylinder wall and so to arrange said nozzle that is discharges a fuel jet through a window formed in the piston skirt and substantially toward the position head. In that engine the interior of the hollow piston is substantially closed from the crankcase. The transfer port and the fuel injection nozzle are provided on that side which is opposite of the exhaust port. That arrangement will result in the formulation of an improved mixture because at lest a part of the fuel jet will impinge on the piston head, which is that part of the piston that is at the highest temperature during the operation of the engine. Besides, the piston head is cooled because the energy corresponding to the latent heat of eva-oration is extracted from the piston head. Finally, a stratified charge is formed in the combustion chamber because the rich mixture enters the combustion chamber on that side which is opposite to the exhaust pot and only a very poor mixture flows from the crankcase case into the cylinder chamber through those transfer ports which are nearer to the exhaust port. As a result, only a poor mixture can flowing the worst case into the exhaust port. This will result in an improved fuel consumption and in an improved composition of the exhaust gas. But in that teaching the requirements of an operation under light load and for a fast response of the engine and the conditions resulting from a fast opening of the throttle valve have not been taken into account.